Cover for control units



Oct 24, 1939. N SCHELLENGER 2,177,286

COVER FOR CONTROL UNITS Filed Sept. 4, 195'? 2 Sheets-Sheet l JNVENTOR. [YE wrozv GScHz'LLzWGHZ.

HTTOHNEY 1939. N. c. SCHELLENGER 2 9 COVER FOR CONTROL UNITS Filed Sept. 4, 1937 2 Sheets-Sheet 2 INVENTGR.

1V5 wrozv CT S01E13 L ENGER. .BY 7

ATTORNEYS Patented Oct. 24, 1939 when stares FATENT GFFECE COVER FOR CONTROL UNITS Application September 4, 1937, Serial No. 162,415

4 Claims.

The present invention relates to housings or covers for rheostats, and more particularly to housings or covers especially adapted for use with rheostats used for volume control and tone corn 5 trol purposes in radio receiving sets.

Such rheostats usually comprise a variable resistance unit including a base carrying the. resistance and actuating mechanism and a metallic cover or housing. The cover has been formed with an end wall and with an integral side wall or flange drawn from a single sheet of metal to a sufiicient depth to house the rheostat parts. The side walls engage the base of the rheostat or in many cases overlap the base to a certain extent,

if) the side wall or flange being formed with projections along the edge thereof which are bent over into engagement with the base to complete the rheostat assembly. In such assemblies the axial spacing between the variable resistance unit and the cover or housing is secured by providing an insulating strip around the inside face of the flange or side wall which strip abuts the end wall of the housing and said base. Inasmuch as the variable resistance unit usually includes terminals secured to the upper face of base, it has been necessary to provide a cut-out portion in the housing side wall to give suiflcient clearance for the terminals and to provide for a positive location of the housing in respect to the base. The

cut-out portion has been formed by a separate operation after the drawing of the side wall or flange, which additional step in the formation of the cover tended to relieve strains in the flange or side wall, thus allowing the cover to open up to a considerable degree. This release of strains destroyed the flt between the cover and the base to such an extent that a great deal of hand work was often necessary to put them in condition so that the same could be used. Furthermore,

where it became necessary to provide a second cut-out to give clearance for a tap terminal, the condition of the cover after this second operation was much worse, necessitating further and additional hand work to place the cover in condition for use. Still another objection to this form of construction was that when the side wall or flange was drawn to a substantial depth so as to facilitate a connection of the cover to the base of the unit, considerable scalloping of the lower edge of the flange was introduced into the cover construction, thus making the height of the side wall or flange sufficiently uneven to make it difficult to properly clinch the projections over the base. Still another objection to the construction as described above was that a further operation was necessary to provide a stop Within the cover which, in a good many instances, did not have the required strength necessary in a device of this kind.

Various attempts have been made to entirely 5 eliminate any additional cutting work upon the covers after the blank forming the same has been shaped. Such attempts, however, were not entirely successful inasmuch as there was a tendency for the ears or lugs to drift or float circumferen- 1U tially, resulting in considerable variation in the location of such lugs or projections, it being recognized that variation in the location of such projections was due to the variation of the temper, the thickness of the stock sheet and the drawing 15 conditions, as well as other factors, and that probably such variation was tremendously exaggerated because of the fact that the ears or projections of the design under consideration were in certain instances well supported on one side while sub- 20 stantially no support was present on the other side.

The present invention therefore has to do primarily with improvements in the cover or housing construction for such rheostats, such improvements consisting in the necessary changes not only in the design for the side walls of these covers or housings, but also in the manner of procedure in the process of making the same.

More particularly, an object of the present in- 30 vention is to provide a cover which is drawn from a stock sheet to a substantially uniform depth to provide the necessary clearance for the usual terminals as well as tap terminals when desired, and to provide ears or projections in respect to the intermediate portions of the flange which are of substantially uniform depth so that the ears or projections will be supported by the same amount of metal on each side and will therefore draw straight instead of floating circumierenw tially or drawing at an angle to an element of the cylindrical flange of the cover.

Still a further object of the present invention is to provide a cover or housing as above described in which the ears or projections are positioned with respect to the grain structure of the stock blank so that the variations in the drawing will be balanced out to a considerable extent.

An additional object of the present invention is to provide a novel housing or cover for a rheostat 5U wherein the side wall or flange is of such a design and shape and the lugs or projections included as a part thereof are so positioned with respect to the grain structure of the stock blank that a single drawing operation only is necessary to pro- 5 duce the finished product, thus eliminating all additional cutting or trimming operations heretofore necessary and thereby eliminating any possibility of relieving stresses in the side wall or flange which would affect the diameter or position of the projections thereof.

Still a further object of the present invention is to provide a cover or housing for a rheostat of such a design and so cut or stamped from the stock blank that the projections or ears forming part of the side wall or flange will be accurately located after the drawing operation to register properly with the notches in the periphery of the base of the variable resistance unit.

It is another object of the present invention to provide a novel housing or cover as above described in which a stop may be provided therein during a single drawing operation, thus avoiding the further necessity for additional operations in the construction thereof.

Other objects, features, capabilities and advantages are comprehended by the invention, as: will later appear and as are inherently possessed thereby.

Referring to the drawings:

Figure 1 is a view in side elevation of a rheostat or variable resistance made in accordance with the present invention;

Figure 2 is a bottom plan view of the rheostat shown in Figure l of the drawings;

Figure 3 is a plan View of a blank for the housing of the rheostat and showing the positioning of the elements thereof in respect to the stock blank and the grain structure thereof from which the same is cut;

Figure 4 is an exploded view of the rheostat of Figure 1 of the drawings, the elements thereof being shown in perspective to disclose the structure thereof more in detail;

Figure 5 is a fragmentary view in elevation showing a typical lug construction formed in line with the grain of the metal of the housing and its cooperative relation with the resistance unit;

Figure 6 is a fragmentary View in elevation corresponding to Figure 5 of the drawings, showing a typical lug construction for a housing which is offset in relation to the grain of the metal forming the same and showing its cooperative relation with the resistance unit;

Figure 7 is a fragmentary view in crosssection through a part of the rheostat housing showing the construction of the indented stop therein and its cooperative relation with the insulating band associated with the housing;

Figure 8 is a view partly in elevation and partly in cross-section of the rheostat shown in Figure l of the drawings, the cross-sectional part thereof being through the terminal connection therefor;

Figure 9 is an exploded View of a switch assembly including a rheostat corresponding to that shown in Figure 1 of the drawings, the elements thereof being shown in perspective to disclose the structure more in detail; and

Figure l0 is a cross-section of a cover with an insulating lining partially assembled thereon.

Referring now more in detail to the drawings, a rheostat selected to illustrate the present invention is shown as comprising a variable resistance unit 2 and a cover or housing 4 which is connected thereto, will be more fully described hereinafter.

The variable resistance unit 2 comprises a shaft 6 which is journalecl in the thimble 8 and carries the disc H] which is retained on the inner end of the shaft 6 by the swaged inner end ll of said shaft, this shaft serving to control the variable resistance device and the thimble 8 being threaded to connect the unit to a panel or chassis flange in the usual well-known manner, for example, by means of a nut (not disclosed) which is screwed upon the threaded portion of the thimble 8.

Secured to the thimble 8 is a washer l2 upon which, in abutting relation, is disposed a metal shield plate I3 and a base M of insulating material, the latter being of substantially circular construction except for the extended terminal carrying portion IT. The base l4 supports the disc 3 which has a film or layer of resistance material upon the upper surface thereof. The extended portion ll of the base serves as a support for a plurality of terminals 22, 24 and 26. Mounted upon the upper end of the shaft 5, and positively driven by the disc H! by means of the inwardly projecting lug 28 cut therefrom, is an insulating disc 30. To disc 30, by means of a rivet 32, is secured'a collecting ring having a contactor cooperating with the film or layer of resistance material on the disc l8, all of this structure being well-known and therefore not disclosed in detail in the present application.

The end terminals 22 and 26 are mounted on the upper face of the extending portion ll as by means of the hollow rivets 34 and 36, respectively, the bases of said terminals, respectively, being provided with the side lugs 38 and 4!) fitting recesses 42 and 44 to prevent displacement thereof and said bases being in conductive relation with the film or layer of resistance material on the disc IS. The intermediate terminal 24, however, is connected to the extended portion H by means of the rivet 46 which also connects it to the conductor 48 disposed on the lower surface thereof which is electrically connected to the collecting ring in the usual manner.

The base I4 is provided with notches 5B, 52, 54, 56, 58 and 60 disposed in spaced relation circumferentially thereof and adjacent the periphery for receiving a plurality of projections or ears l2, (0, B8, B6, 54 and 62, respectively, of the cover or housing 4.

The present invention is particularly directed to the formation of this cover or housing 4, and as illustrated in Figure 3, the same is formed by drawing a blank 14 stamped from a strip or sheet of material shown in dotted lines as at 16. The stamping 14 comprises, within the circular dotted line as at 82, aportion which forms the end wall 84 of the cover or housing, it being understood that the stamping T4 is drawn so that the outer annular part 85 including the projections or ears B2, 64, 66, 58, 10 and 12 is drawn into the cylindrical form as shown in Figures 1 and 2 of the drawings to provide the side wall or flange 88 of the housing. The marginal edges of the portion 8% between the adjacent projections or ears are formed to provide the cut-out portions 90, 92, 94, 95, 98 and I06 in the completed housing, as clearly shown in Figure 4 of the drawings, the depth of the Wall or flange at such cut-out portions being substantially equal so that each of the lugs or projections is supported by the same amount of metal on each side.

It has been found that by providing this construction and cutting the stamping as shown in Figure 3 of the drawings whereby the lugs 54 and 10 are substantially in alignment with each other and in alignment with the grain structure of the sheet of material I6, as indicated by the double headed arrow shown at I02, variations in the drawing operation will be balanced out to a considerable extent and floating or circumferential drift of the lugs will be substantially eliminated. As a matter of fact, it has been found that because of the uniformity in depth of the flange or wall 88 at the cut-out portions and stamping of the metal in the manner indicated in Figure 3, the drift is so under control that it is possible to dispose lugs 64 and Ill as shown in Figure 3 in a slight offset relation as shown at I04 and I66 in respect to the center line as represented at I138. The cut-out portion I06, as shown in Figure 1 of the drawings, provides suitable clearance for the terminals 22, 2d and $26, and wherever a tap terminal is desired any other of the cut-out portions may be used to provide the necessary clearance therefor.

During the drawing operation the housing is cut along the lines iii? and 5 52 at the junction of the end wall 84 and the side wall or flange 88 and the intermediate portion therebetween struck inwardly to provide an indented stop I I4, as clearly shown in Figure 8 of the drawings, and which, when the rheostat is assembled, cooperates with the upwardly extending lug i It on the disc 10 to limit the rotative movement thereof, it being also observed that this disc H3 is provided with an upwardly extending switch operating pin H8 which may be provided for the purpose of operating a switch mechanism, as will be hereinafter more fully set forth.

The rheostat, as assembled, includes an insulating strip I26 cut to the proper length so as to be disposed adjacent the inner face of the cylindrical flange 38 of the housing with the ends I22 and I24 cut on a bias, as shown in Figure 4 of the drawings, so as to facilitate the placing of the same within the housing, it being understood that by the formation of the ends as disclosed, one end may be placed in position and the other end easily pressed into position in abutting relation thereto in the manner clearly shown in Figure 10.

One end I22 is first placed in proper position in the cover as shown in Figure 10 and the strip curled into the position shown which leaves the two ends somewhat out of alignment. As the cover 4 is pressed into place on the control, end i24 of the insulating strip is aligned with end I22 which exerts an expanding action on the insulating strip and causes it to fit firmly against the flange at all points.

This insulating strip is provided with a notch 26 along one edge thereof which embraces the stop ll l to properly position this strip within the housing and preventing relative rotation in respect thereto. The opposite edge of the strip is provided with the stepped notches 528 and I}, the central portion thereof fitting over the bases of the terminals 22 and 25, respectively, and the marginal shoulders of these notches, as at 32 and I34, fitting over the extensions on the resistance element I8 that carry terminals 22 and 26, respectively. Further, the intermediate portion I36 between notches I28 and I30 is disposed between the extension of the resistance element I8 as shown in Figure 8 to form a close fit with the extending portion II adjacent the intermediate terminal. The edge portions at either side of the notches F28 and I3t are disposed in abutting relation with the base I4 of the variable resistance unit, Whereas the opposite edge portions of the strip on either side of the notch I26 abut the end wall 88 of the housing, thereby properly positioning the cover or housing axially in respect to the base, the insulating strip furthermore closing the openings between the base and the side wall or flange 83 formed by the cut-outs 92, 9d, 96, $8 and Hill,

Each of the lugs 62, t l, 66, Bil, iii and "I2 is similarly formed to provide the main part I38 depending downwardly from the flange, intermediate part I40 of less width to provide shoulders I42 and Hi l therebetween and an end part N6 of less width than the intermediate part I43 to provide shoulders Mil and i5il therebetween, said part I46 being of less width in order to facilitate bending without distorting the adjacent portions of the lugs or projections. The intermediate parts liiil of the projections or ears are received within slots formed in the periphery of the base so that shoulders M2 EM do not engage the base it since the insulating strip 429 positions the base axially with respect to the housing when the end parts i l'i are bent over into engagement with the bottom face of the base. It will be noted that the notches 58 and 52 are of substantially the same width as the intermediate portions Hit of projections ii and I0, respectively, and are so positioned on the base I l as to provide a close fit with said intermediate portions of lugs fi l and to accurately position the housing 6 circumferentially with respect to the base i l.

On the other hand, notches 53, 54, 55 and 5d are of slightly greater width than the intermediate portions l lii of lugs i2, 58, and 62, respectively, to provide suitable amount of clearance, as for example at and 54, to accommodate a limited amount of variation in the positioning of said projections or ears which may be due to drift, it being noted in this connection that said ears or projections are angularly disposed with respect to ears 8% and it as formed in the stamping it and that ears 64 and it are substantially aligned with the grain. structure of the strip 16. Inasmuch as the disposition of the projections 54 and Hi can be accurately determined in the housing when the stamping is cut from the strip '55 as shown in Figure 3, the notches 58 and 52 are designed to closely cooperate therewith to position the housing and the base and the clearances 52 and E54 provided in the remaining notches to accommodate slight variations in the position of the remaining projections due to drift or the slight mac-- curacies in the formation of the notches in the base cooperating therewith.

It will be quite apparent from the above disclosure that the rheostat assembly discloses improvements wherein it is possible by a single operation to fabricate a housing from a single piece of material, drawing and cutting the same to provide stop EM as well the projections which will accurately position the housing in respect to the variable resistance unit and to provide sufficient clearance for terminals such as 22, 24 and 26, as well as a tap terminal, if desired, without resorting to a multiplicity of operations. Furthermore, successively (formed housings or covers are of substantially the same dimensions and the projections or cars correspondingly disposed in relation to the end wall thereby eliminating additional hand operations which would otherwise be necessary during assembly of the housing and unit. Still further, covers made in accordance with the present disclosure have the side wall or flange thereof of substantially uniform depth sufficient to provide clearance for the terminals but hearing such a ratio to the diameter of the end wall that scalloping has been eliminated, thus making it unnecessary to perform additional work to fit the housing to the base. The present design for the housing also definitely locates the housing with respect to the unit. These devices therefore can be manufactured and assembled readily and easily by simple operations and at a greatly reduced cost, and the particular assembly results in improved operation of the same.

When it is desired to use the rheostat as hereinbefore described and disclosed in Figures 1 to 8 inclusive in conjunction with a switch, the construction. of the end wall 84 of the housing is slightly modified as clearly shown in Figure 9 of the drawings to include a cut-out 200 and the slots 2G2, 254, 206 and 208, the remaining structure of the rheostat shown in this figure corresponding to the construction shown in Figures 1 to 8 inclusive, and the same being assembled in the manner hereinbefore described. In the embodiment disclosed in Figure 9 of the drawings, the assembly includes a snap switch 218 provided with the housing 242 formed with a plurality of lugs H4, H5, 2H3 and 220 adapted to be received in and extend through the slots 202, 204, 206 and 208, respectively, and turned over on the underside of the end wall 84 whereby said housing is securely fastened in place on the housing 4 of the rheostat assembly. This snap switch comprises the switch mechanism generally designated as 222 which is disposed within the housing 2 l2 and includes the cam 224. This cam cooperates with the operating pin I I8 through the opening 200 in the end wall whereby the cam 224 is rotated upon rotation of the shaft 6 of the rheostat assembly to operate the switch mechanism.

While I have herein described and upon the drawings shown an illustrative embodiment of the invention, it is to be understood that the invention is not limited thereto but may comprehend other constructions, arrangements of parts, details and features without departing from the spirit of the invention.

I claim:

1, In an electrical device, the combination of a variable resistance having a base provided with a terminal support extending therefrom, said base being provided with a plurality of peripheral notches, a metallic housing for said resistance comprising a member having an end wall and a cylindrical flange, a stop formed from said housing and extending into the same, said flange having cut-out portions providing a plurality of projections adapted to be disposed in said notches and secured to said base, said flange between said projections being substantially the same depth, and a cylindrical insulating strip disposed within said housing and adjacent said flange and engageable with said end Wall and base to position said base and housing, said strip having a notch adapted to receive said stop to prevent displacement thereof in said housing and additional notches adapted to receive said terminals.

2. In an electrical device, the combination of a variable resistance having a base provided with a terminal support extending therefrom, said base being provided with a plurality of peripheral notches, a metallic housing for said resistance comprising a member having an end wall and a cylindrical flange, a stop formed from said housing and extending into the same, said flange having cut-out portions providing a plurality of projections adapted to be disposed in said notches and secured to said base, one of said cut-out portions being or greater width than the others to provide an opening for said support and terminals, said flange between said projections being substantially the same depth, and a cylindrical insulating strip disposed Within said housing and adjacent said flange and engageable with said end wall and base to position said base and housing, said strip being of substantially greater width than the depth of the flange and having a notch adapted to receive said stop to prevent displacement thereof in said housing and additional notches adapted to receive said terminals.

3. In an electrical device, the combination of a variable resistance having a base provided with a terminal support extending therefrom, said base being provided with a plurality of peripheral notches, a metallic housing for said resistance comprising a member having an end Wall and a cylindrical flange, said flange having cut-out portions providing a plurality of projections adapted to be disposed in said notches and secured to said base, one of said cut-out portions being of greater width than the others to provide an opening for said support and terminals, the said projections next adjacent the said projections defining said last-named cut-out portion being substantially oppositely disposed and co-- operating with certain of said notches in said base to position said housing with respect thereto, and said flange between said projections being substantially the same depth, and a cylindrical insulating strip disposed Within said housing and adjacent said flange and engageable with said end wall and base to position said base and housing, said strip being of substantially greater width than the depth of the flange and having notches adapted to receive said terminals.

4. In an electrical device, the combination of a current carrying unit, a housing for said unit, said housing having a substantially cylindrical wall, an insulating band disposed on the inside face of said cylindrical wall, said band having the ends thereof disposed in abutting relation and said ends being out upon complementary angles to facilitate assembly and to expand the band into firm engagement with the substantially cylindrical Wall of the housing.

NEWTON C. SCHELLENGER. 

